Armor-piercing projectile and cap therefor.



R. A. HADFIELD.

ARMOR PIERCING vPROJECTILF. AND CAP THEREFOR.

Patented Feb. 22, 1916.v

I 3 SHEETS-SHEET I- R A. HADFIELD.

1914. n Patented Feb; 22, 1916.

3 SHEETS-SHEET 2- I PN wm M f,

a. A. FIELD.- K E ARMOR PIERCING PRO E ILE AND CAP THEREFOR. i

LICATIN FILED NOVB, 1907- RENEWED JUNE 20 |914 APP y f y1,172,278 Patented Feb.22,1916.

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lToall whom it concern.' Be itqknownthat I, ROBERT'ABBOTT' Han-l r1nLo,` ;a subject of the King .of Great Britain and Ireland, residing at Sheiield, in the county lof York, England, have invented v. pri'ximately .the shape \.shown,='with a. .charge "Improve1i ents.-innor Relating to y Armorj Piercing,'-'Projectiles and CapsThere'for, of

v which the following is a specification;v

`This invention-has reference tothe manufacture or production of a'rinorpiercing projectiles having great penetrative power and'4 range, acharge chamber of as large capace. ity as that of vwhat areknown as common ory bursting shell, of'correspondingsize, and

as 'compared lwith ,the weaker and unhardened head liability to accidentall ignition of the charge i through prematureor spontaneous fracture j ectile.

The invention-also has reference to im- I- proveniente in the construction of caps for i. use with armor piercing projectileswhereby not only; isA the efficiency .ofthe caps im-1 provedbut alsothe flight oftheprojectiles Figure lfshows,'1nvlongitudinal section, af

v portion ofv a twelve'inch'icapped projectile scale, thewhole'of the capped projectile.

.of a slightly'modified. construction of such capped, projectile, andFig. 4V is 'a diagram.

2. i, The projectile. lis `constructed of high te.

nacity steel, such asnickel steehor nickel Mchromium Isteel. It is preferably made 4'of nickel chromium steel containing from about I f per cent.) of; chromium, land from fiabout 1.5% to, 25% v(one decimal five. to'two deci- V about 0.45% (decimal four.-ve `per..cent.)

l Eloi-atten", zteelt The silicon should: not. usually,

yet havingI a much stronger a'ndh'arder head (one decimal *six inches); ..;The 1 bur`sting vi1' such common shell, vand nonchamber is made about' equal in. capacity/to .i

of the head or hardenedportion vof the pro-V .ac'cordingl to theinvention; Fig.' 2 shows in l. {.longitudinal central section-'and'to aV reduced i Fig. 3 shows, in longitudinal section, partyV S to 7% .(decimal sixfftodecimalseven per cent) of carbon, from about 1.5% Ito `2.5% (onedecimal yve'totwo decimal `five mal :five per cent..)"of nickel. Manganese, -while preferably'keptglow, may go -up. to

- The projectile is. ,p1oduced by I'casting it of. steelof the kndaref'erred: to2 and' of 'ap-l or bursting;r chanibee,l 1F61? n {iwelve Cinch..."4 i

projectile, the headportion-foe-is made'o an.;` axial length a 1. an`2 ofsay about. (seven'and three eighthvinches) land with a *shoulder-'6 f of a thickness, sayiat the line-.cf c, ofabout' (three and ahaifiaches),iheehicimess l gradually diminishing.rearwa'rd: to the part where thev wall d1. of.' the 'bursting chamberd is o-f a unlform 'thicknessfofg say about 156-v that of an ordinary or bursting s helland for a considerable portionwf its-length 4is of mentioned, o'r nearly so. v The-curvefa1--a-" of the ogival h eaclportionuv of .the projectilel 'shown in Figs. lfand2.isfcirciilarandnmay. correspond or. approximate to a-radius of;

quartcr-t1mesthe diameter. f the projectile, preferably l`to the diameter multipliedV by -1 v1.74. (one decimal sevenv four), the ogvalflfl5 surface of the heada 4c 0'rresp'ondin'gto that of afs'olid of revolution formed bythe i' 'i tation. ofthe. portion lol-a3 ofthe ellipse, 4

adjacent; 'tothe minora'xis ww, about' th e*'y i 'i ylongitudinal .exista1 a%.of the'projectile.`

the case of al twelve'inch projectile, whose real diameter is about `11.9 5. (eleven decif. ff

75" cylindricalshape, 4as Shown, its rear., end f .being continuedof practically or s'ubstan- *1 tially' the lfull. diameterthrollghfthe bagiefof',

.85" i .fabouttwiceithe.diameter orcaliber. ofthe projectile,viz. 'twentyfour inches. 1nv the".- v case of` the twelve inch- :projectile shown.

'.diusto'w'a'rd the point a3. The curve x1-a3 L j preferably forms, as shown in FigsrBand 4', part of an ellipse whosel semiminoraxis a; .is equal tor about thediameter 'of they projectile,preferably yto the dia rneter plus.10.9.` 'A (decimal four) and whose semi-major axis y g/ is equal to about oneand three mal nine five inches), the semi-minorl axis (twelve decimal three five inches). and the semi-major axis jz/ g/ will be 11.95" 1.74= 20.8 (twenty decimal eight inches). The axial length a1-a5 of the ogival head portion of the projectile may be equal to about 1.2 one decimal two) times the diameter of the projectile, that is to say, for a 12 inch projectile, about 11.95 1.2:14.3 (fourteen decimal three inches).

The form of head just described has been found to give better results in practice than the old form of head with a true radius, as regards its ability to perforate armor and is believed to be theoretically correct for armor perforation and probably also for range.

The projectile constructed as described, is"

then subjected to annealingand hardening and stiffening treatments such as described in the specification of my former British Patent No. 15219 of 1904, except that the head of the projectile is immersed to a less depth than before, in the cooling or hardening liquid, say to a depth of from about six to nine inches in the case of a twelve inch made of two diiferent radii,

shell. y

' The projectile thus produced vis .provided with a metal cap having `an obtuse conical pointed portion e and an acute conical fear portion e1, these two portions being joined by a curved or rounded surface preferably the front end portion e2 of such curved surface being of smaller radius than the succeeding portion e3'. Inthe example, the conical front portion c hasanA angle o: of about 150 (one hundred and fty degrees), and the rear end portion e1 an angle of about 36 (thirty l six degrees); the forward ogive portion e2 of the cap is made of small radius, say about 1.5 (one decimal five inches) for the twelve inch shell shown, and the rearward ogive part e3 of a larger radius, say of about 4.7 (four decimal seven inches). The shape of thefront' end portion of the cap may be arrived at as follows: The axial thickness ml-wl of the cap having been determined, about 2% (two and three eighth inches) in the example, line w1 m2 at an angle 6 of about 15 (fifteen degrees) to a transverse plane y, y at the end of the cap are marked oif and a width z e of about 2.9 (two decimal nine inches) set out. The lines a .e1 jo'ning the'ends of the line a z to the base of the cap are then drawn, forming a truncated cone having an angle of about 36 (thirty-six degrees). With its center on the axial line w1 w1 and with a radius of about 1.5 (one decimal five inches), an arc forming the curved 'portions e2 is then struck so that the lines w1 are tangential thereto, and with a radius of about 4.7 (four decimal seven inches) arcs forming the curved portions e3 .is however deemed advantageous to make the whole of the cap of the relative shape and dimensions indicated for a twelve inch projectile. For projectiles of other diameters, the dimensions of the cap will usually be proportionate to those indicated, or nearly so, except that the angles ofthe conical portions will be maintained at about those mentioned. The cap may be made of wrought iron, or of mild steel suitably toughened, as by heating it to a temperature between 950 C. and 1100o C. (nine hundred and fifty and eleven hundred degrees centigrade) then cooling itin air or other cool ing medium, but preferably quickly, as by quenching in water or other liquid, afterward reheatig 'it to a temperature of between about 6000 C and 800.C. (six hun dred and eight hundred degrees centigrade), according to the toughness desired, and cooling it slowly. v j

The cap may be secured to the projectile in any desired andapproved manner. `In the example,it is securedby depressing portions of its base into a numbercf notches or recesses asin the head of thel projectile.

The rear end of the charge chamber d is screw-threaded at d2 to Yreceive a corre-Vl land closely fitting the inner surface of the chamber d. For this purpose, the liner, which may be made of'sheet copper of about three one-hundredths of an inch thick, may be made as a hollow body'of approximately the shape of the chamber and be forced into close Contact with' the inner surface thereof, which may be in its ordinary cast conditioh, by expanding it, as by an elastic or expansible core. The rear open end of the liner is extended backward suliciently to surround the forwardly projecting end f1 of the base closing plug f which is made of slightly' less diameter than the remainder of the plug so as to t into and close the rear end'of the liner and securely hold the liner in place in the projectile. By the construction described, the liner z' can be readily fitted into the projectile and securely fixed in place therein at any time after the projec- Armor piercing capped :projectiles or shells constructed as hereinbefore described,

'liner secured-in place as. described, any lia- .i

bility of the bursting charge belng accidentally ignited by a spark produced byy premature or spontaneous fracture v.of the.

v head or hardened portion of the projectile, 2o either when being fired, or while in store, will be prevented. Alsocaps constructed as described can advantageously be used" with armor piercingprojectiles other than those of the special construction hereinbe- .25 fore described and shown in the drawings. As best shown in Fig. 2 the cap is shortA and small as 4compared to the, projectile, the length of the v.portion of the cap'in front of the projectile point being less than one iif# teenth the total length of the projectile, and said cap portion being.l in length vsubstanltially one third the length 'of -said projectile potioni'n front' of the'chamber and the cap extending back over- .I'nore than about two thirds of said projectile portion in frontofthe chamber whereby4 the capv is firmly se.-

cured in place. y g

' l. An armor piercing shell provided' with 40 al steelcap, said cap having an obtuse conical point, 'an acute conical rear portion/and an intermediate curved surface merging into the end portion andthe rear portion,'said curved surface being, of two radii of different lengths, the front portion of said curved .surface beingof a shorter radius. and the' rear portion of. alonger.

2. An armor piercing projectile provided y with a metal cap comprising a conical front end portion having an angleof conieity of about/150 degrees,-a conical rear portion 3 having anangle of conicity of about 36 de- ."radii inthe proportion of about 1.5 inches and 4.74 'inches for a twelve inch projectile, substantially as described.

3. A'cap for an armor'piercing shell, hay7M ing an obtuse conical point, thl'sides of the conical point being substantia y at, an an v @il gie of 159 toa plane transverse to the end of` the point, said cap having an acute conical rear portion and. a curved portionl intery mediate the point and the rear portion.

4. .An armor'pfiercing projectile'. made of high tenacity steel and having an ogival head the surface of which, in longitudinal section, is'in the form of a segment of an ellipse as set forth, and a metal cap attached to, said hed and having an obtuse angled conical front end portion, anaeute 'angled' conical re'arfend portionand an intermediate portion .havlng ar-cwved surface in longitudlnal section, the side walls of the capextending back adjacent to a transverse plane through the front end of the chamber.

5. An .armorpiercing shell fitted with a vsmall light cap and having a charging chamber not substantially less in length than three-quarters the len h of'l the shell and being substantially cy indrical throughout the greater portion of Iits; length, the various parts of the shell and cap being made in about the following Vproportions as com pared to a twelve inchshell, namely vthe axial length of the shell head from the chamber to the tip about seven and three-eightlis inches,'the thickness of theshellwall at the shoulder about three and onehalf inches, and the thickness of. the wall tapering therefrom to a uniform thickness of about one and six-tenths inches; the axial length of the cap being about two and three-eighths inches and tapering therefrom to its end about the shoulder.

, Signed at 28 Hertford street, Mayfair, London, England, this vfourteenth day of' October, 1907.

ROLBER'I ABBOTT HADFIELD. n

Copies of this patent may be obtained for ve cents leach, by adressing' the Commissioner of Patents, i' Washingtomnc. 

